<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>HTML Example</title>

  <!-- External CSS link -->
  <link rel="stylesheet" href="styles.css">

  <!-- Internal CSS style -->
  <style>
    body {
      font-family: 'Arial', sans-serif;
      background-color: #f0f0f0;
      margin: 0;
      padding: 0;
    }

    header {
      background-color: #333;
      color: white;
      padding: 10px;
      text-align: center;
    }

    section {
      margin: 20px;
    }

    h1 {
      color: #333;
    }

    p {
      line-height: 1.5;
    }
  </style>
</head>

<body>

  <!-- Header -->
  <header>
    <h1>HTML Example</h1>
  </header>

  <!-- Main Content -->
  <section>
    <p>This is a concise example of an HTML file demonstrating major language features.</p>
    <ul>
      <li>Document structure with DOCTYPE and HTML tags</li>
      <li>Meta tags for character set and viewport</li>
      <li>Title tag for setting the page title</li>
      <li>External CSS link and internal CSS style</li>
      <li>Header, section, and paragraph elements</li>
      <li>Unordered list</li>
    </ul>
  </section>

</body>

</html>